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Introduction
Rock excavation is the first process in the cycle of operation of a mine, and efficient blasting is paramount to the profitability of the mine. The traditional way to design blasts has been by trial and error, based on the experience of the designer. This is probably the only important engineering practice which continues to be done without a precise engineering technique. The efficiency of most other mine processes has been improved by the use of high tech, while a majority of blast design has not yet profited from the advantages of the computer.
However, with the advent of the Blaspa high-tech blast simulator, it has become possible to design the parameters of the blast according to normal engineering practices. Over the last 50 years, the chemical and physical mechanisms which occur during a blast have come to be identified; they are reviewed by Favreau (1969, 1985, 1994). Although these mechanisms are complex, they have nevertheless been expressed in terms of mathematical equations which have been assembled together in the computer to create the blast model Blaspa.
This model is very comprehensive. Each blast simulation on Blaspa monitors, during the entire blast action, the chemical reactions of the ingredients which the explosives manufacturer has put into the explosives used in the blast, and simulates all the shock waves and stress fields that fragment the rock everywhere in the bench, as well as the subsequent displacement of each fragment of rock to form the muck-pile.
The simulation takes into account the full geometry of the blast design, i.e., the pattern, hole diameter, collar, subgrade drilling, distribution of the explosives, water in the hole, etc. But most important, it takes into account the specific properties of the rock at the mine: Young's modulus "Y," Poisson's ratio "s," the density "d" and the dynamic resistance of the rock "To."
The Blaspa simulator has been made userfriendly in that the effects of the blasting action of the simulated shock waves, stress front and rock displacement are translated into practical outputs to which the user can easily relate: the expectation of large blocks and how to prevent them; the possibility of toe; the weakening of the rock at the back of the blast and how it promotes back-break;...